Conventionally, for example, as proposed in JP 2012-196022 A, there is known a solar power generation system which includes a solar cell provided with solar panels, an electric storage device and a charge control device for charging the electric storage device with an electric power generated by the solar cell. In such a solar power generation system, when the solar cell generates an electric power, in other words, when the sun shines, the charge control device is configured to be activated to charge the electric storage device with an electric power output from the solar cell. In general, the charge control device includes a charger for charging the electric storage device, a voltage sensor for detecting an output voltage (a generated electric power voltage) of the solar cell and a microcomputer for controlling an operation of the charger. When the generated electric power voltage detected by the voltage sensor exceeds a set voltage, the microcomputer activates the solar power generation system to operate the charger, thereby to start charging the electric storage device.